Support for chair

ABSTRACT

A support for a chair includes: a base plate ( 110 ); support plates ( 120, 130 ), of which one sides are rotatably coupled to the base plate ( 110 ); and a first hinge ( 150 ) which connects the base plate ( 110 ) and the support plates ( 120, 130 ) to be rotatable, wherein the base plate ( 110 ) is supported by a seat portion ( 11 ) of a chair ( 10 ) and the support plates ( 120, 130 ) are supported by a back portion ( 12 ) of the chair ( 10 ) while the base plate ( 110 ) and the support plates ( 120, 130 ) are unfolded at a first maximum unfolding angle (θ 1   m ) and support the upper body of a user.

TECHNICAL FIELD

The present disclosure relates to a support for a chair, particularly, asupport for a chair that is mounted on a chair in use.

TECHNICAL FIELD

In generally, a chair, which is a tool that is used for a person to sit,is composed of a seat that supports the hips when a user sits, and aseat back that is disposed at the rear of the seat and supports thewaist of a user. In some cases, legs are additionally provided under theseat or a neck support is additionally provided, and they are configuredin various ways in accordance with the use purposes, for example, thelegs are fixed or are provided with casters at the lower end to beeasily moved and the neck support supports the head of a user.

Various waist support technologies for supporting the waist when a usersits on such a chair have been disclosed.

For example, there is a waist support that protrudes at both sides witha predetermined depth at the center of a seat back so that the waist isseated when a user leans the back against the seat back.

Since such a waist support supports only the waist of a sitting user, ithas limitation in terms of comfort or convenience and has technologicallimitation that it cannot completely remove a load that is applied to awaist.

Meanwhile, airplanes, long-distance buses (expressway buses andcross-country buses), express trains of transportation are beingincreasingly frequently used due to diversification of life, work, etc.of modern people.

Since the reclining angles of the seat backs of the seats in airplanes,long-distance buses (expressway buses and cross-country buses), expresstrains are limited, when a user sits for a long time, a large load isapplied to the waist, the sitting comfort is poor, and there is alsoinconvenience.

Further, when a user moves a long distance in the seat in an airplane, abus, a car, an express trains, etc., the load of the upper body istransmitted to the hips, so there is a problem that the sitter feelspain due to pressure on the hips by such transmission of a load.

Disclosure Technical Problem

The present disclosure has been made in an effort to solve the problemsdescribed above in the related art and an objective of the support for achair according to the present disclosure is to provide a support for achair that,

first, provide a sitting comfort as if a user obliquely lies on a bedeven when sitting on a chair, thereby being able to provide excellentsitting comfort and comfort,

second, can remarkably reduce a load that is applied to the waist orprevent a load from being applied to the waist when sitting,

third, can provide sitting comfort like obliquely lying when sitting fora long time in a seat with a small gap, particularly, in an airplane, along-distance bus, a car, an express train, etc., thereby being able toprovide excellent ease and comfort,

fourth, can remove a pain due to pressure on the hips by the load of theupper body transmitted to the hips when moving in a seat in an airplane,a bus, a car, an express train, etc, and

fifth, can minimize the volume and reduce the thickness because it canbe folded after used, thereby being able to remarkably improveconvenience for carrying and keeping the product.

Technical Solution

In order to achieve the objective of the present disclosure, a supportfor a chair (a back and waist support for a chair), which is a supportfor a chair that is mounted on a chair including a seat and a seat backto support the rear of the upper body of a user, includes: a base plateof which the lower end is supported on the seat of the chair; a supportplate of which a first side is rotatably coupled to the base plate and asecond side is supported on the seat back, and that supports the rear ofthe upper body of a user in close contact with the rear of the upperbody of the user; and a first hinge that is connected to the upper endof the base plate and the first side of the support plate, therebyrotatably connecting the base plate and the support plate, in which thebase plate and the support plate are folded or unfolded by the firsthinge, and when the base plate and the support plate are unfolded at afirst maximum unfolding angle with the base plate supported on the seatof the chair and the support plate supported on the seat back of thechair and the weight of the upper body of a user is applied, the baseplate and the support plate maintain the first maximum unfolding angle,thereby supporting the upper body of the user.

Advantageous Effects

A support for a chair having this configuration according to the presentdisclosure has the following effects.

First, there is an effect that it is possible to provide a sittingcomfort as if a user obliquely lies on a bed even when sitting on achair, thereby being able to provide excellent sitting comfort andcomfort.

Second, there is another effect that it is possible to remarkably reducea load that is applied to the waist, and in some case, it is possible toprevent a load from being applied to the waist when sitting.

Third, there is an effect that it is possible to provide sitting comfortlike obliquely lying when sitting for a long time in a seat with a smallgap, particularly, in an airplane, a long-distance bus, a car, anexpress train, etc., thereby being able to provide excellent ease andcomfort.

Fourth, there is an effect that it is possible to remove a pain due topressure on the hips by the load of the upper body transmitted to thehips when moving in a seat in an airplane, a bus, a car, an expresstrain, etc.

Fifth, there is an effect that it is possible to minimize the volume andreduce the thickness because it can be folded after used, thereby beingable to remarkably improve convenience for carrying and keeping theproduct.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a support 100 for a chair according toan embodiment of the present disclosure and a state view in which thesupport is mounted.

FIG. 2 is an exemplary view of a use state in which a user uses thesupport 100 for a chair according to an embodiment of the presentdisclosure.

FIG. 3 is an exemplary view of a use state when a second support plate130 is folded and used as a two-stage support 100 in the support 100 fora chair according to an embodiment of the present disclosure.

FIG. 4 is a perspective view seen from the inside of the support 100 fora chair according to an embodiment of the present disclosure.

FIG. 5 is an exploded perspective view of FIG. 4 .

FIG. 6 is an operation view of the support 100 for a chair according toan embodiment of the present disclosure.

FIG. 7 is an operation view in which a base plate 110 is folded in thesupport 100 for a chair according to an embodiment of the presentdisclosure.

FIG. 8 is an operation view in which the second support plate 130 isfolded with the base plate 110 folded in the support 100 for a chairaccording to an embodiment of the present disclosure.

FIG. 9 is an exemplary view of a use state when a support plate isconfigured one support plate 120 and the support 100 for a chairaccording to an embodiment of the present disclosure is configured as atwo-stage support as a modified example.

MODE FOR INVENTION

Next, a preferred embodiment of a support for a chair of the presentdisclosure is described in detail with reference to the accompanyingdrawings.

The support for a chair of the present disclosure is technically a waistsupport for a chair, etc.

The “outside” of the support 100 described in the specification is adirection facing a user and the “inside” of the support 100 is adirection facing a chair.

A support 100 for a chair (a back and waist support 100 for a chair)according to an embodiment of the present disclosure, which is a support100 for a chair that is mounted on a chair 10 including a seat 11 and aseat back 12 to support the rear (the back, the waist, or the back andwaist) of the upper body of a user, includes: a base plate 110 of whichthe lower end is supported on the seat 11 of the chair 10; a supportplate 120, 130 of which a first side (a lower end when mounted on achair) is rotatably coupled to the base plate 110 and a second side (anupper end when mounted on a chair) is supported on the seat back 12, andthat supports the rear (in detail, the back and the waist) of the upperbody of a user in close contact with the rear (in detail, the back andthe waist) of the upper body of the user; and a first hinge 150 that isconnected to the upper end 111 of the base plate 110 and the first side(lower end) of the support plate 120, 130, thereby rotatably connectingthe base plate 110 and the support plate 120, 130.

Further, the first plate 110 and the support plate 120, 130 are foldedor unfolded by the first hinge 150. When the base plate 110 and thesupport plate 120, 130 are folded, they can be fully folded inward suchthat the insides come in contact with each other. When the base plate110 and the support plate 120, 130 are unfolded at a first maximumunfolding angle θ1 with the base plate 110 supported on the seat 11 ofthe chair 10 and the support plate 120, 130 supported on the seat back12 of the chair 10 and the weight of the upper body of a user isapplied, the base plate 110 and the support plate 120, 130 maintain thefirst maximum unfolding angle θ1, that is, are not folded at an anglelarger than the first maximum unfolding angle θ1, thereby supporting theupper body of the user.

When a user leans on the support 100 with the hips on the seat 11, theback and waist of the user are both supported, and particularly, theback is supported much, whereby it is possible to reduce or completelyremove the load applied to the waist when the user sits and it ispossible to achieve an effect that the user is like obliquely lying on abed while sitting on a chair.

In particular, when a user sits in a seat with a small gap in anairplane, a long-distance bus, a car, an express train, etc., the usercan obliquely sit and lie, whereby there is an advantage that ease andcomfort can be provided and it is possible to reduce or remove a loadthat is applied to the waist when sitting. Further, this effect may beincreased in a chair 10 with a neck support 13.

Further, since the support 100 can be folded and unfolded, it ispossible to fold the base plate 110 on the support plate 120, 130 afterusing the support 100, so there is an advantage that it is possible toreduce the volume and thickness and easily and conveniently carry andstow the support.

In particular, since the base plate 110 and the support plate 120, 130are thin plates, they can be kept in a handbag or a backpack, soconvenience for keeping and carrying is further improved.

It is preferable that the base plate 110 and the support plate 120, 130are made of a synthetic resin material. Accordingly, it is possible toreduce the weight of the product, so there is an advantage thatportability is further improved.

Since the support 100 is light, has a small volume, and is thin, it ispossible to carry and move the support 100 in a handbag or a backpackand then simply take out and use the support 100 when sitting in anairplane, a long-distance bus, an express train, etc., so convenience ofuse is remarkably improved.

The first maximum unfolding angle θ1 m is an obtuse angle (an anglelarger than 90° and smaller than 180°).

Preferably, the first maximum unfolding angle θ1 m is an obtuse angle of120˜160°. More preferably, an unfolding angle of 130˜150° is formed.More preferably, an unfolding angle of 135° is formed.

The unfolding operation is stopped by contact of the upper end 111 ofthe base plate 110 and the first side (lower end) of the support plate120, 130, whereby the first maximum unfolding angle θ1 m is maintained.

Further, the support further includes a stopper 141 protruding from theupper end 111 of the base plate 110 or the first side (the lower end inthe drawings) of the support plate 120, 130 to set the first maximumunfolding angle θ1 m between the base plate 110 and the support plate120, 130.

Further, when the stopper 141 is formed at the base plate 110, thesupport plate 120, 130 is stopped at the stopper 141, whereby the firstmaximum unfolding angle θ1 m is formed. When the stopper 141 is formedat the support plate 120, 130, the base plate 110 is stopped at thestopper 141, whereby the first maximum unfolding angle θ1 m is formed.

Although an example in which the stopper 141 is formed at the upper end111 of the base plate 110 in the embodiment shown in the figures, thepresent disclosure is not limited thereto and it is apparent that thecase in which the stopper is formed at the lower end of the supportplate 120, 130 (in detail, the lower end 122 of a first support plate120) is also included in an embodiment of the present disclosure.

The stopper 141 integrally protrudes from the upper end 111 of the baseplate 110 toward the support plate 120, 13.

Accordingly, since the stopper 141 integrally protrudes from the upperend 111 of the base plate 110, depending on which view is selected, itmay be considered that the upper end 111 of the base plate 110 protrudesand the protruding upper end 111 of the base plate 110 and the lower end122 of the support plate 120, 130 (or the first support plate 120) arestopped by coming in contact with each other, whereby the first maximumunfolding angle θ1 m is formed.

When the first support plate 120 and the second support plate 130 areunfolded, the upper end of the first support plate 120 and the lower end132 of the second support plate 130 come in contact with each other,whereby the unfolding operation is stopped. Accordingly, the firstsupport plate 120 and the second support plate 130 maintain a maximumunfolded state, that is, a second maximum unfolding angle θ2 m.

Accordingly, there is an advantage that the second maximum unfoldingangle θ2 m is set and maintained by the configuration of the two supportplates 120 and 130 themselves.

As shown in FIGS. 1 to 8 , the support plate 120, 130 is composed of aplurality of support plates 120 and 130 that are rotatably connected toeach other by one or more second hinges 160.

The first side (lower end) of any one of the plurality of support plates120 and 130 is rotatably coupled to the base plate 110, the second side(upper end in the figures) of the other one of the plurality of supportplates 120 and 130 is supported on the seat back 12, and the pluralityof support plates 120 and 130 are unfolded and support the rear of theupper body of a user in close contact with the rear (waist and back) ofthe upper body of the user.

As shown in FIGS. 1 to 8 , in the support 100 for a chair according toan embodiment of the present disclosure (referred to as a three-stagesupport 100 in the specification), the support plate 120, 130 includes afirst support plate 120 rotatably connected to the base plate 110 by thefirst hinge 150 and a second support plate 130 rotatably connected tothe first support plate 130 by the second hinge 160.

In this configuration, the first side (lower end 122) of the firstsupport plate 120 is rotatably coupled to the base plate 110, the secondside (upper end) of the second support plate 130 is supported on theseat back 12 of the chair 10, the first and second support plates 120and 130 are connected by the second hinge 160 to be able to be unfoldedand folded with respect to each other, and the first and second supportplates 120 and 130 are unfolded and support the rear of the body of auser in close contact with the rear (waist and back) of the upper bodyof the user. The base plate 110 and the first support plate 120 arefolded or unfolded by the first hinge 150. The base plate 110 and thefirst support plate 120 are unfolded at the first maximum unfoldingangle θ1 m, whereby the base plate 110 is supported on the seat 11 ofthe chair 10. When the weight of the upper body of a user is applied tothe first and second support plates 120 and 130 with the first andsecond support plates 120 and 130 unfolded and the second support plate130 supported on the seat back 12 of the chair 10, the base plate 110and the first support plate 120 maintain the first maximum unfoldingangle θ1 m (i.e. are not unfolded at an angle larger than the firstmaximum unfolding angle θ1), and the first support plate 120 and thesecond support plate 130 maintain the second maximum unfolding angle θ2m, thereby supporting the upper body of the user.

Even though a plurality of support plates 120 and 130 are provided, asdescribed above, the maximum unfolding angle θ1 m is an obtuse angle(angle larger than 90° and smaller than 180°).

The maximum unfolding angle θ1 m is an obtuse angle of 120˜160°,preferably, is an unfolding angle of 130˜150°, and more preferably, anunfolding angle of 135°. This is because stable and easy sitting comfortis provided.

The support 100 further includes a stopper 141 protruding from the upperend 111 of the base plate 110 or the lower end 122 of the first supportplate 120 to set the first maximum unfolding angle θ1 m between the baseplate 110 and the first support plate 120, which was described above.

When the stopper 141 is formed at the base plate 110, the first supportplate 120 is stopped at the stopper 141, thereby forming the firstmaximum unfolding angle θ1 m, and when the stopper 141 is formed at thefirst support plate 120, the base plate 110 is stopped at the stopper141, thereby forming the first maximum unfolding angle θ1 m, which wasalso described above.

In the support 100 for a chair according to an embodiment of the presentdisclosure, the base plate 110 and the second support plate 130 can befolded to be sequentially stacked with the first support plate 120therebetween that is positioned at the center of three plates 110, 120and 130. Accordingly, there is an advantage that it is possible tominimize the three-step support 100 and reduce the thickness thereof.

When the first support plate 120 and the second support plate 130 areunfolded, they are unfolded such that the outer surfaces 120 b and 130 bof the first and second support plates 120 and 130, respectively, formthe same plane.

Accordingly, the first and second support plates 120 and 130 thatsupport the back of a user are flat, so the user can more comfortablylean.

In this case, the second maximum unfolding angle θ2 m of the firstsupport plate 120 and the second support plate 130 is 180°.

When the first support plate 120 and the second support plate 130 areunfolded, the upper end of the first support plate 120 and the lower end132 of the second support plate 130 come in contact with each other,whereby the unfolding operation is stopped. Accordingly, the firstsupport plate 120 and the second support plate 130 maintain a maximumunfolded state, that is, a second maximum unfolding angle θ2 m.

Accordingly, there is an advantage that the second maximum unfoldingangle θ2 m is set and maintained by the configuration of the two supportplates 120 and 130 themselves.

Further, the base plate 110 is folded with respect to the first supportplate 120 such that the inner surface 120 a of the first support plate120 and the inner surface 110 a of the base plate 110 come in closecontact with each other or face each other, and then the second supportplate 130 is folded with respect to the first support plate 120 suchthat the inner surface 130 a of the second support plate 130 and theouter surface of the base plate 110 come in close contact with eachother or face each other, whereby the first support plate 120, the baseplate 110, and the second support plate 130 are sequentially stacked andfolded in that order.

Further, base reinforcement ribs 115 are formed on the inner surface 110a of the base plate 110, first reinforcement ribs 125 are formed on theinner surface 120 a of the first support plate 120, and secondreinforcement ribs 135 are formed on the inner surface 130 a of thesecond support plate 130.

An edge 114 protrudes inward along the edge of the base plate 110, apair of protruding edges 124 protrudes along the left and right edges ofthe first support plate 120, and a pair of second protruding edges 134protrude along the left and right edges of the second support plate 130.Further, the base plate 110 is folded with respect to the second supportplate 130 such that the edge 114 is positioned inside the firstprotruding edge 124, and the second support plate 130 is folded withrespect to the first support plate 120 such that the second protrudingedge 134 covers the base plate 110 in close contact with the firstprotruding edge 124 with the base plate 110 folded. Accordingly, thefirst support plate 120, the base plate 110, and the second supportplate 130 are sequentially stacked and folded in that order.

Further, the edge 114 of the base plate 110 is composed of a side edge114 a protruding along the left and right edges and a lower end edge 114b protruding along the edge of the lower end of the base plate 110, andreinforcement rib seat grooves 116 for accommodating the firstreinforcement ribs 125 are concavely formed at the lower end edge 114 b.

The first hinge 150 includes a first hinge bottom bracket 151 formed atthe upper end of the base plate 110, a first hinge top bracket 152formed at the lower end 122 of the first support plate 120, and a firsthinge pin 153 connecting the first hinge bottom bracket 151 and thefirst hinge top bracket 152. The first hinge may further include a firstnut 154 that is thread-fastened to the first hinge pin 153.

The second hinge 160 includes a second hinge bottom bracket 161 formedat the upper end of the first support plate 120, a second hinge topbracket 162 formed at the lower end 132 of the second support plate 130,and a second hinge pin 163 connecting the second hinge bottom bracket161 and the second hinge top bracket 162. The second hinge pin 153 mayfurther include a second nut 164 that is thread-fastened to the secondhinge pin 153.

Meanwhile, as shown in FIG. 9 , according to a modified embodiment ofthe support 100 for a chair according to an embodiment of the presentdisclosure, it ma be composed of two plates, that is, the base plate 110and the first support plate 120 (which is referred to as a two-stepsupport in the specification), and of course, this case is also includedin the technical range of the present disclosure.

Any of the two-stage support 100 and the three-stage support 100 areincluded in the technical range of the present disclosure. The two-stagesupport 100 and the three-stage support 100 just selected and used by auser on the basis of the size of a chair or the size of the user's body.

Meanwhile, the use example shown in FIG. 3 is an example in which athree-stage support 100 is composed of three plates, that is, the baseplate 110 and the first and second support plates 120 and 130 and onlythe base plate 110 and the first support plate 120 are used as thesupport 100 by folding the second support plate 130.

It was exemplified that the support plate 120, 130 is composed of twosupport plates 120 and 130 in the support 100 for a chair according toan embodiment of the present disclosure, but the present disclosure isnot limited thereto, and the case in which the support is composed ofthree support plates or four support plates is included in the technicalrange of the present disclosure, and all cases are included in thetechnical range of the present disclosure regardless of the number ofsections.

Next, the operation of the support 100 for a chair having the aboveconfiguration according to an embodiment of the present disclosure isdescribed.

First, the operation of folding and using is described.

The support 100 is unfolded by maximally unfolding the base plate 110 atthe first maximum unfolding angle θ1 m and folding the second supportplate 130 at the second maximum unfolding angle θ2 m.

The lower end of the base plate 110 is supported on the seat 11 and theupper end of the second support plate 130 is supported on the seat back12, whereby the support 100 is mounted on the chair 10.

As shown in FIG. 2 , when a user obliquely lies such that the waist ispositioned substantially at the boundary between the base plate 110 andthe first support plate 120 and the back is positioned at the first andsecond support plates 120 and 130, the user feels very comfortable andeasy like lying on a bed with a back seat erected.

In this case, a partial load F1 of the weight of the user is appliedsubstantially at the boundary between the base plate 110 and the firstsupport plate 120, but even if the load F1 is applied, the first maximumunfolding angle θ1 m can be maintained. Further, another load F2 of theuser is applied substantially at the boundary between the first supportplate 120 and the second support plate 130, but even if the load F2 isapplied, the second maximum unfolding angle θ2 m can be maintained.

Reference numeral θ1 is a first unfolding angle θ1 that is the anglemade between the base plate 110 and the first support plate 120, andreference numeral θ2 is a second unfolding angle θ2 that is the anglemade between the first support plate 120 and the second support plate130.

Next, a folding operation of keeping or carrying is described.

First, the base plate 110 is folded (FIG. 7(b)) in the state in whichthe base plate 110 and the second support plate 130 are both unfolded(FIG. 7(a)). As shown in FIG. 7(b), the base plate 110 is fully insertedbetween the first protruding edges 124 at the right side inside thefirst support plate 120.

Next, the second support plate 130 is folded with the base plate 110folded (FIG. 8(a)), whereby the support is fully folded (FIG. 8(b)). Asshown in FIG. 8(b), when the second support plate 130 is folded, thesecond protruding edge 134 and the first protruding edge 124 are incontact with each other, whereby a neat externals shape is formed.

A preferred embodiment according to the present disclosure was describedabove, but it is apparent to those skilled in the art that the presentdisclosure may be implemented in other concrete ways without changingthe spirit or necessary features of the present disclosure other thanthe embodiment described above. Accordingly, it should be understoodthat the embodiment described above is not limitative, but exemplary.

The scope of the present disclosure is defined by the following claimsrather than the above detailed description, and all of changes andmodifications obtained from the meaning and range of claims andequivalent concepts should be construed as being included in the scopeof the present disclosure.

1. A support (100) for a chair that is mounted on a chair (10) includinga seat (11) and a seat back (12) to support the back of a user, thesupport (100) comprising: a base plate (110) of which a lower end issupported on the seat (11) of the chair (10); a support plate (120, 130)of which a first side is rotatably coupled to the base plate (110) and asecond side is supported on the seat back (12), and that supports therear of the upper body of a user in close contact with the rear of theupper body of the user; and a first hinge (150) rotatably connecting thebase plate (110) and the support plate (120, 130), wherein the baseplate (110) and the support plate (120, 130) are folded or unfolded bythe first hinge (150), and when the base plate (110) and the supportplate (120, 130) are unfolded at a first maximum unfolding angle (θ1 m)with the base plate (110) supported on the seat (11) of the chair (10)and the support plate (120, 130) supported on the seat back (12) of thechair (10) and the weight of the upper body of a user is applied, thebase plate (110) and the support plate (120, 130) maintain the firstmaximum unfolding angle (θ1 m), thereby supporting the upper body of theuser.
 2. The support of claim 1, wherein an upper end (111) of the baseplate (110) and the first side of the support plate (120, 130) arestopped by coming in contact with each other, whereby the first maximumunfolding angle (θ1 m) is maintained.
 3. The support of claim 1, whereinthe support plate (120, 130) is composed of a plurality of supportplates (120) and (130) that are rotatably connected to each other by oneor more second hinges (160), and the first side of any one of theplurality of support plates (120) and (130) is rotatably coupled to thebase plate (110), the second side of the other one of the plurality ofsupport plates (120) and (130) is supported on the seat back (12), andthe plurality of support plates (120) and (130) are unfolded and supportthe rear of the upper body of a user in close contact with the rear ofthe upper body of the user.
 4. The support of claim 3, wherein thesupport plates (120) and (130) include: a first support plate (120)rotatably connected to the base plate (110) by the first hinge (150);and a second support plate (130) rotatably connected to the firstsupport plate (130) by the second hinge (160), the first side of thefirst support plate (120) is rotatably coupled to the base plate (110),and the second side of the second support plate (130) is supported onthe seat back (12) of the chair (10), the first and second supportplates (120) and (130) are connected by the second hinge (160) to beable to be unfolded and folded with respect to each other, the first andsecond support plates (120) and (130) are unfolded and support the rearof the body of a user in close contact with the rear of the upper bodyof the user, the base plate (110) and the first support plate (120) arefolded or unfolded by the first hinge (150), the base plate (110) andthe first support plate (120) are unfolded at the first maximumunfolding angle (θ1 m), whereby the base plate (110) is supported on theseat (11) of the chair (10), and when the weight of the upper body of auser is applied to the first and second support plates (120) and (130)with the first and second support plates (120) and (130) unfolded andthe second support plate (130) supported on the seat back (12) of thechair (10), the base plate (110) and the first support plate (120)maintain the first maximum unfolding angle (θ1 m), and the first supportplate (120) and the second support plate (130) maintain a second maximumunfolding angle (θ2 m), thereby supporting the upper body of the user.5. The support of claim 4, wherein the base plate (110) and the secondsupport plate (130) can be folded to be sequentially stacked with thefirst support plate (120) therebetween that is positioned at a center.6. The support of claim 2, further comprising a stopper (141) protrudingfrom the upper end (111) of the base plate (110) or the first side ofthe support plate (120, 130) to set the first maximum unfolding angle(θ1 m) between the base plate (110) and the support plate (120, 130). 7.The support of claim 6, wherein when the stopper (141) is formed at thebase plate (110), the support plate (120, 130) is stopped at the stopper(141), whereby the first maximum unfolding angle (θ1 m) is formed, andwhen the stopper (141) is formed at the support plate (120, 130), thebase plate (110) is stopped at the stopper (141), whereby the firstmaximum unfolding angle (θ1 m) is formed.
 8. The support of claim 6,wherein when the first support plate (120) and the second support plate(130) are unfolded, the first and second support plates are unfoldedsuch that outer surfaces (120 b) and (130 b) of the first and secondsupport plates (120) and (130), respectively, form the same plane. 9.The support of claim 4, wherein base reinforcement ribs (115) are formedon an inner surface (110 a) of the base plate (110), first reinforcementribs (125) are formed on an inner surface (120 a) of the first supportplate (120), and second reinforcement ribs (135) are formed on an innersurface (130 a) of the second support plate (130).
 10. The support ofclaim 4, wherein an edge (114) protrudes inward along an edge of thebase plate (110), a pair of protruding edges (124) protrudes along leftand right edges of the first support plate (120), a pair of protrudingedges (134) protrudes along left and right edges of the second supportplate (130), and the base plate (110) is folded with respect to thesecond support plate (130) such that the edge (114) is positioned insidethe first protruding edge (124), and the second support plate (130) isfolded with respect to the first support plate (120) such that thesecond protruding edge (134) covers the base plate (110) in closecontact with the first protruding edge (124) with the base plate (110)folded, whereby the first support plate (120), the base plate (110), andthe second support plate (130) are sequentially stacked and folded inthat order.